This invention relates generally to bicycles, and, more particularly, to the construction of a recumbent bicycle.
Bicycles are vehicles having two wheels mounted, one behind the other, to a frame upon which the rider sits. The bicycle is conventionally driven by the rotation of pedals connected to a crank arm, which in turn rotates a front sprocket. The front sprocket is connected to the rear wheel by a chain and rear sprocket, so that rotation of the pedals forces rotation of the rear wheels. Alternatively, the bicycle may be powered by a small engine. The front wheel is mounted to a front fork that in turn is connected to movable handlebars, permitting the front wheel to be turnably steered by turning of the handlebars. In the United States, bicycles are now largely used for recreation, while in some countries they provide a primary means of transportation.
In the conventional or standard bicycle, the rider sits generally upright on a saddle-like seat about 36 inches above the ground (depending upon the length of the rider's legs and personal preference), and the pedals and front sprocket are generally vertically directly below the center of gravity of the rider. The rider is thus in a sitting position, but is largely vertical and can quickly rise from the seat to a standing position, so that more force can be applied to the pedals. The standard bicycle is familiar to most persons, and has become highly popular as an efficient, if rather slow, means of transportation and recreation.
In another form of bicycle, the recumbent bicycle, the rider sits closer to the ground on a bench-type seat, in a true sitting position with his legs extending forwardly. The pedals and front sprocket are well in front of the rider, but are pedaled in the same fashion to power the bicycle. The recumbent bicycle has important advantages over the standard bicycle in reduced wind resistance, better downhill performance, and increased comfort of the bench seat over the saddle seat.
The recumbent bicycle is used in bicycle speed trials and in specialty racing, but has not generally received the widespread acceptance of the standard bicycle, despite its many advantages. One reason for its lack of acceptance is a result of the design restrictions imposed upon the recumbent bicycle by the relative positioning of the front wheel and the crank spindle upon which the pedals are mounted. Since the front wheel must be free to rotate, in typical recumbent bicycles the transverse crank spindle is supported to the frame either behind the front wheel, above the front wheel, or in front of the front wheel. When the crank spindle is behind the front wheel, the bicycle becomes very long and difficult to steer, because the frame must be long enough for the rider's legs to extend forward to the pedals, and must have additional length to support the front wheel forward of the crank. When the crank spindle is in front of the front wheel, the front wheel must be made sufficiently small to fit between the rider's legs, so that the rider's legs can comfortably reach forward to the pedals. This arrangement leads to highly unstable handling characteristics, short life for the small front wheel, and an inability to maintain supplies of front wheels (and rear wheels, in those cases where the rear wheels are made the same size as the front wheel). When the crank spindle is located above the front wheel, the front wheel must be made smaller than that of the standard bicycle due to the length of the rider's legs. Even with reduced size of the front wheel, in some designs the rider's legs are inclined upwardly, so that blood tends to leave the rider's legs and long term pedalling becomes fatiguing. The upward inclination of the legs gives the rider a sense of instability and insecurity, adding to the problem of decreased stability of handling.
There therefore exists a need for a recumbent bicycle which has the established advantages of recumbent bicycles generally, but also has an improved construction that avoids the problems of prior recumbent bicycles. Such a recumbent bicycle should have an intermediate length wheelbase which is long enough for good stability and short enough for good steerability, and which is comfortable and efficient for rides of extended duration. Such an improved recumbent bicycle would, it is believed, add greatly to the acceptability and use of recumbent bicycles. The present invention fulfills this need, and further provides related advantages.